Sliding snow and/or ice from roofs can be hazardous to people, the surrounding landscape, property, and building components. For example, snow or ice sliding from a roof above an entryway may injure passers-by. Similarly, falling snow or ice can do damage to landscape features, such as shrubs, and property or building components, including automobiles or lower roofing portions. In addition, sliding snow or ice can shear off antennas, gutters or other components attached to a building roof or wall, thereby potentially causing a leak. The problem of sliding snow or ice is particularly experienced in connection with metal roofs, including raised seam roofs (e.g., standing seam), where there is relatively little friction between the roof and the snow or ice. As used herein, the term "raised seam roofs" includes roofs formed by a series of panels interconnected to define longitudinal, raised portions. It may therefore be desirable to provide a guard suitable for controlling movement of snow and/or ice across/along selected areas of such metal roofs.
Snow guard devices were initially developed for use on tile and shingle roofs. In one type of configuration for use on such roofs, an L-shaped brace has one leg which is fastened to the roof and another leg which projects upwardly from the roof. The fastening leg is typically nailed or screwed into the roof beneath a shingle or tile. By positioning and attaching a plurality of these braces to the roof in substantially linear fashion, linear bars may be positioned within/through one or more receiving areas of the respective upwardly projecting legs to provide a fence-like configuration for snow and/or ice retention. U.S. Pat. No. 97,316 to Rogers, issued Nov. 30, 1869, U.S. Pat. No. 106,580 to Hathorn, issued Aug. 23, 1870, U.S. Pat. No. 250,580 to Rogers, issued Dec. 6, 1881, and U.S. Pat. No. 756,884 to Parry, issued Apr. 12, 1904, are generally representative of this type of device.
A device which employs a similar structure to the above but which does not require the individual braces to actually be affixed to the roof is presented in U.S. Pat. No. 42,972 to Howe, issued May 31, 1864. In this case, the plurality of braces for receiving the linear bars are positioned on opposite sides of the roof and are interconnected by a harness assembly. By positioning the brace/bar assemblies on both sides of the roof, the snow retention device is presumably held in position.
Other snow retention devices for shingle or tile roofs have utilized a unitary construction For instance, U.S. Pat. No. 459,876 to Powers, issued Sep. 22, 1891, discloses a snow guard having two, laterally displaced spikes which are driven into the roofing surface, with the interconnecting portion of the spikes having a generally V-shaped configuration which extends downwardly toward the roofing surface. U.S. Pat. No. 602,983 to Folsom, issued Apr. 26, 1898, discloses a device used with a tiled roofing surface having grooves formed such that the spikes or leg portions of the device may be positioned therein. An interconnecting portion between the spikes or legs in this instance incorporates a loop-like configuration.
Another snow retention device is the SNOWJAX.TM. snow guard which is believed to be the subject of U.S. Pat. No. 4,141,182 to McMullen, issued Feb. 27, 1979. This device comprises a plastic barrier having a generally L-shaped cross-section. The device can be installed by smearing the underside of the device with silicon intended to provide a weather seal, positioning the device against the roof surface, and attaching the device to the roof with screws such that the screws penetrate the roofing surface and become anchored into an underlying structural member. An adhesive may be used in place of the screws where desired.
The ThyCurb division of Thybar Corporation has also marketed a snow guard device for use on trapezoidal-type, standing seam roofs having 24 inch wide panels. The device comprises a horizontal steel member which spans one panel width. The horizontal member is fixedly attached at ends thereof to mounting members which straddle the trapezoidal panel ribs. These mounting members are fastened to the panel ribs by screws.
There are a number of problems generally associated with one or more of the snow guard devices described above. First, such devices may cause the roof to leak. Many of the devices described above are attached to the roof by a screw, nail or other fastener which pierces the roofing surface. Such piercing of the roof can lead to undesired leakage due to inadequate sealing or shearing of the fastener by the forces exerted thereon by sliding snow and/or ice. In an attempt to prevent leakage, sealants and/or gaskets are often applied around the holes pierced through the roofing surface. However, these measures complicate installation and may not fully prevent leaks. Known alternative methods for attachment of snow guard devices to roofs (e.g., adhesive bonding), may fail to provide secure attachment, particularly where the device is applied to a smooth, non-porous roofing material such as metal.
Many known snow guard devices can also cause undesired pinning of the roofing materials. Metal roofing sheets are often designed to be moveable so as to accommodate normal thermal expansions and contractions. Where snow guard devices such as described above are attached to the roof by a screw, nail or the like, which pierces the roofing surface and is anchored into an underlying structural member or deck, the designed thermal movement characteristics of the roof can be compromised, thereby adversely affecting the roof's performance.
The types of snow guard devices described above are also generally not readily adaptable for use in a broad range of raised seam roofing applications. Some of the devices described above are not intended for raised seam roofing applications at all but, rather, are primarily for use on shingled or other non-raised seam roofs. Other known devices are designed for use on raised seam roofs having a particular panel width and seam profile and cannot be easily adjusted for use in connection with panels of differing widths or seams of various profiles. Moreover, some known devices are designed to be permanently connected to a roof such that the device cannot be easily repositioned as may be desired. In addition, known snow guard devices generally comprise a snow blocking element having a height, relative to the roof surface, which is unadjustable, difficult to adjust, or adjustable only between a small range of predetermined positions. Accordingly, the user's ability to adjust such devices, as may be desired to suit particular conditions with respect to snowfall, drifting and the like, is limited.